String tensioning device for musical instruments



Feb. 25, 1947. G. PROLLv '2,416,593

STRING TENSIONING DEVICE FOR MUSICAL INSTRUMENTS Filed Aug. 11, 1945 Patented Feb. 25, 1947 STRING TENSIGNING DEVICE FUR MUSICAL INSTRUMENTS Gusta-ve Proli, Newark, N. il.

Application August 11, 1945, Serial No. 610,323

1 Claim. 1

This invention relates to means for adjusting the tension of strings on stringed instruments or the violin type, and especially for tensioning of metallic strings of the larger sizes of instruments, such as cellos, base viols and the like; and the invention has reference, more particularly, to an improved tensioning device for appiication to the tail-piece of a stringed instrument, whereby, upon manipulation of the device, a very accurate final tuning of the string served thereby may be attained.

String tensioning devices as heretofore provided have comprised a pivoted bell-crank lever mounted on a base so attached to the instrument tail-piece that the upstanding arm of the bell-crank and the end of the base to which said bell-crank lever is pivoted are disposed to project beyond the free forward end of the tail-piece. rhis is objectionable, not only as unsightly, but

for the further reason that such projecting parts are not rmly supported against vibration, so that undesirable buzzing or humming is likely to occur.

it is an object of this invention to provide a novel construction of string tensioning device which, when operatively mounted on an instrument tail-piece, lies wholly within the confines of the free forward 'end of said tail-piece, and which is so related to the latter that the base of the device is iirmly abutted throughout its total length against the tail-piece body, and thus held tightly against vibration relative to the latter; the construction being of such novel character that the upstanding arm of the bell-crank lever can be inserted upwardly through the eye or large end of a key-hole type opening with which the tail-piece is provided, and then moved forward to extend upwardly through the notch or slot end of said opening, said arm being formed to provide a thin blade-like body portion of less thickness than the width of said slot end, whereby to be freely oscillatable within the latter; the base of the device having a threaded opening adapted to register with the eye or large end of the tail-piece opening, when disposed in operative assembled relation to the tail-piece, said threaded opening being adapted to receive the clamp screw for afxing said base in place, and said clamp screw being adapted to receive an adjusting screw threaded therethrough and manipulatable to operatively engage and bear on the underlying bottom arm of the bell-crank lever.

The invention has for another object to provide the upstanding arm of the bell-crank lever with a novel string seating fork or double hook adapted to receive the anchoring .ball of a ballstring.

Other objects of this invention, not at this time more particularly enumerated, will be understood from the following detailed description of the same.

.en illustrative embodiment of this invention is shown in the accompanying drawings, in which:

Eig.' l is a longitudinal sectional view showing the and pivoted bell-crank lever as initially applied to an instrument 4tail-piece preparatory to mounting the same thereon; -Fig. 2 is a similar view showing the base and pivoted bell-crank lever shifted to operative position on the tailpiece ready to be anixed to the latter by the clamp screw of the device; Fig. 3 is a similar view showthe complete device operatively assembled with and aiiixed to the tail-piece; Fig. 4 is a top plan view of the device as operatively assembled with and amxed to the tail-piece; and Fig. 5 is a cross-sectional view, taken on line 5 5 in Fig. 3, the device being shown in elevation.

Similar characters of reference are employed in the above-described views to indicate corresponding parts.

the drawings, the reference character Iii indicates the tail-piece of a stringed instrument, the same being provided with lthe usual key hole ordinarily employed to receive anchoring attachment oi the instrument strings to said tailpiece; said key hole slots each comprising an eye or enlarged rear end portion il and a notch or slot end forwardly extending therefrom.

The novel string tensioning device according to this invention comprises a base plate I3 having a bifurcate forward end portion formed by a reentrant slot lli. intermediate said bifurcate forward end portion and the rear end of said base plate i3, the base plate is provided with an internally screw-threaded opening Entered in the slot it of said base plate i3 is the upstanding arni of a bell-crank lever which comprises said upstanding arm l and a rearwardly extending bottom arm ll which underlies said base-plate. Said bell-crank lever is pivotally connected with said base-plate by a transverse pivot or fulcrum pin iii. Said upstanding arm oi the bell-crank lever comprises a thin blade-like body portion of less thickness than the width oi' the notch or slot end l2 of a tail-piece key hole slot. Said upstanding arm of the bell-crank lever terminates, at upper tree end, in a rearwardly open bifurcate or forked hook element 2d adapted to receive the ball or anchor piece 2E of a ball string 22 desired to be served by the tensioning evice. Said bifurcate or forked hook element 2d is of overall lateral or horizontal cross-sectional dimensions less than the diameter of the eye or enlarged rear end portion il of a key hole slot of the tail-piece it, whereby said element 2i) may be passed upwardly through said eye or enlarged rear end portion of the key hole slot.

To apply the string tensioning device to the instrument tail-piece, the base plate I3 is passed beneath the latter and disposed so that the upstanding arrn iis of the bell-crank lever is axially aligned with the eye or enlarged rear end portion ll of a selected key hole slot oi said tail-piece; whereupon the base plate is raised to abut the underside of the tail-piece, thus causing' the upstanding arm it of the bell-crank lever, together with the bifurcated or forked hook element 2@ thereof, to pass upwardly through said eye or enlarged part ll of said key hole slot (see Fig. l). When the base plate i3 and bell-crank lever are thus positioned, the base plate is slid forward along the underside of the tail-piece it, so that the blade-like body portion i9 of the bellrank lever enters the notch or slot end i2 of the key hole slot whereby to be lodged therein, while at the same time the screw-threaded opening la of the base plate i3 is moved into axial alignment with the eye or enlarged part il of said key hole slot (see Fig. 2). As thus disposed, the base plate i3 is ready to be affixed to the tail-piece. The means for aihxing said base plate lfd to the tail-piece comprises a clamp screw having an enlarged head portion 2li; said head portion being preferably provided with a transverse driving slot 25 'adapted to be engaged by a screw driver or like tool. Said clamp screw 23 is passed downwardly through the eye or enlarged part il of the key hole slot, and then screwed into the screwthreaded opening iii of the base plate i3 until the head portion Zfl is stopped and frictionally bound against the top surface oi the tail-piece; said head portion exceeding in diameter, the diameter of the eye or enlarged part il of the key hole slot (see Figs. 3 and 5).

Said clamp screw 23 is provided with an internally screw threaded axial bore Eil. rThreaded into and through said bore is an adjusting screw 2l having a head il@ at its upper end by which it can be manipulated. The lower end 2li-l of the adjusting screw El is caused to abut or bear against the bottom arm il of the bellcrank lever (see Fig. 3).

When the string tensioning devices is assembled with and affixed to the tail-piece in the manner and position above described, it will be noted that the saine lies wholly within the connes of the free forward end of said tail-piece; furthermore, it will be noted that the base plate i3 of the device is iirnily abutted throughout its entire length against the body of the tail-pleo so as to be firmly held tightly against the latter from its front to its rear end, whereby all tendency to vibration relative to the tail-piece is avoided.

In the use of the string tensioninfr device, a string 22 being anchored by its ball or anchor piece 2l to the bifurcate or forked hook element 2li of the bell-crank lever, the string may be tensioned by turning down the adjusting screw 2l through the clamp screw 23 so as to cause the extremity 29 of the former to engage and thrust downwardly upon the bottom arm il of the bellcrank lever, thereby rocking the latter on its pivot or fulcrum pin i3 so as to swing rearwardly the upstanding arm i6, thus stressing the string longitudinally to a desired nicely adjusted and precise degree of tension, whereby to obtain extremely accurate tuning of the string.

It will be observed that the string tensioning device of this invention is very compact, and of minimum bulk, without parts projecting endwise from the inner extremity of the tail-piece, so that but limited portions thereof are exposed to view, with the result that a Very neat and sightly appearance is assured, and yet all the functional advantages being available and subject to easy and quick operation.

Having now described my invention, .l claim:

in combination with the tail-piece of a stringed musical instrument, said tail-piece having a keyhole slot formed by an eye end and a slot end forwardly extending therefrom, of a string tensioning device comprising a base plate having a screw-threaded opening adjacent its rear end, a bell-crank lever pivoted to the forward end portion of said oase plate, the upstanding arm of said bell-crank lever comprising a thin 4bladelile body portion of less thickness than the width oi said slot end of the tail-piece key-hole slot, said upstanding arin of the bell-crank lever terminating in a laterally enlarged bifurcate string anchoring hook element, and the horizontal arm of the bellncranlr lever being disposed to extend rearwardly beneath said base plate to underlie 'the screw threaded opening of the latter, rthe device being adapted to be applied to said tailpiece by passing said upstanding arm and its hook bifurcate element upwardly through the eye end of said lzeyhole slot to abut the base plate against the underside of said tail-piece, and whereupon shifting said base plate forwardly to inove said blade-like body portion of the upstanding arm of the bell-crank lever into the slot end or said key-hole slot with the base plate engaged throughout its length with the underside of the tail-piece and its screw threaded opening aligned with the eye end of the key-hole slot of the latter, a headed clamp screw adapted to be passed downwardly through said eye end of the tail-piece key-hole slot to enter the screw threaded opening of the base plate, said clamp screw havingr an internally screw-threaded axial bore, and a manipulatable adjusting screw threaded through said clamp screw bore to bear upon and actuate said bell-crank lever.

GUSTAVE PROLL.

@FEED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,713,005 Rockwell May 14, 1929 1,792,698 Schulenberg Feb. 17, 1931 

